The recently released 2014 Surgeon General's Report concluded that smoking causes adverse outcomes in cancer patients, and the effects of smoking affect all disease sites and cancer treatment modalities (surgery, chemotherapy, and radiotherapy [RT]). However, most cancer patients do not receive evidence-based cessation support to quit smoking, in part due to several provider-level barriers. Opt-out strategies to clinical care, where all patients are automatically referred to a clinical care program and can later choose not to participate, is one potentially effective method to remove provider-related barriers to evidence-based care. The investigators have piloted large opt-out strategies in cancer patients demonstrating that more than 90% of smoking cancer patients referred through an opt-out strategy are willing to participate in an evidence-based smoking cessation program, while few (1%) participate using an opt-in approach. The objective of this study is to evaluate i an opt-out strategy (vs. opt-in or usual care) can effectively increase smoking cessation rates in cancer patients who smoke at the time of initial consultation for cancer treatment in a radiotherapy clinic. To test this hypothesis, we will randomize 276 patients to an opt-out vs. opt-in strategy for cessation support that provides evidence-based smoking cessation support according to newly released National Comprehensive Cancer Network (NCCN) Guidelines. The primary outcome for Specific Aim 1 (SA1) will be to evaluate smoking cessation rates between each arm with a secondary analysis of adherence to an individualized cessation plan. Specific Aim 2 (SA2) will evaluate the effects of smoking cessation on health-related quality of life (HRQOL) in each arm. Specific Aim 3 (SA3) will evaluate the effect of patient specific moderators on smoking cessation rates in each arm. The results of the proposed study could directly impact evidence-based standards of care for cancer patients and justify consideration of an opt-out approach to improving delivery of other evidence-based care for a spectrum of patients with chronic comorbid diseases such as cancer.